1. Field of the Invention
The present invention is directed to a vehicle brake support assembly for an internally expanding drum brake assembly and, more specifically, to a vehicle brake support assembly for a drum brake which is utilized in heavy duty trucks which include a pair of dual web brake shoes.
2. Description of the Related Art
Heavy duty truck brakes usually include a pair of brake shoes having adjacent ends seated for pivotal movement on a cylindrical surface of a pair of anchor pins mounted to a support plate, often referred to as a "spider" which in turn is secured to a vehicle axle or axle housing. The support plate is usually of elongate form. A rotatable actuating cam and shaft is mounted to the support plate at the end opposite the anchor pins with the cam disposed between the other ends of the brake shoes. During actuation, rotary movement of the cam causes each of the brake shoes to overcome the biasing force of a return spring and to pivot outwardly about the anchor pins into contact with the radially inwardly facing friction surface of a brake drum secured for rotation with a vehicle wheel. The support plate or spider serves as the foundation of the brake assembly and is subject to substantial stress under dynamic braking conditions.
Support plates have therefore traditionally been formed as heavy cast and/or forged members with appropriate areas machined and bored to accommodate the anchor pins and the actuating shaft, and for mounting the support plate to the axle. Such traditional support plates have therefore been expensive to manufacture because of the mass of metal and machining operations required and increased the weight of the vehicles thereby reducing the economics of operation thereof.